The present invention relates to a machine for working flat workpieces with a round, particularly circular outer contour by cutting.
Machines of the above-mentioned general type are known in the art. In a known machine a controlled coordinate table displaces a workpiece in x- and y-directions, a cutting device such as a lazer cutting device acts in a z-direction and a clamping device releasably holds the workpiece on the coordinate table.
In these machines, for example in revolving cutting presses with coordinate tables NC or CNC controlled as a rule or in machines with lazer cutting devices and the coordinate tables, as well as in the revolving cutting presses combined with a lazer cutting device and provided with the coordinate tables, a flat particularly sheet-shaped initial material is generally rectangular. Abutments and clamping elements of conventional coordinate tables are designed for such rectangular workpieces and cuts. In practice, in special application cases, it is required to clamp flat workpieces with a round, particularly circular outer contour and to further work them in the machine. For example, this is generally the case during manufacture of circular saw blades. During manufacture of circular saw blades the hardened round blanks are assembled in a packette and teeth are produced by grinding on special grinding machines. It has been shown that the teeth can be effectively produced by lazer cutting. The manufacture of such circular saw blades by lazer technique is possible on lazer cutting devices or machines of respective type. However, there are considerable difficulties in clamping the round blanks on the coordinate table. For maximum utilization of initial material, the round blanks are cut only with a small surplus relative to the finished saw blade, so that the remaining edge is not sufficient as a clamping strip. This means that after working, the saw blade must be rotated after production of substantially a half of the teeth. This arrangement and process are, on one hand, very time-consuming and, on the other hand, there is a danger that during rotation of the round blank the center will be lost and no perfect exact concentric running of the toothing will be obtained.